The invention concerns a method for controlling a heating system with heating devices in several rooms, the devices being acted upon by a heating fluid with a supply temperature, the heat requirement of the rooms being detected and the supply temperature being adapted to the heat requirement. Further, the invention concerns a heating system with several heating devices; supplied with valves controlled in dependence of the temperature, in various rooms, a supply device with an adjusting member for influencing a supply temperature and a control device, which activates the adjusting member.
A method and a heating system of this kind are known from DE 31 23 649 A1. Here, the opening degree of the thermostatic valves is detected, meaning that it can be sufficient to detect whether the thermostatic valves are opened or closed. When it is established that a thermostatic valve is open, the conclusion is that a heat requirement exists. When a heat requirement exists, the supply temperature is increased. When no heat requirement exists, the supply temperature is decreased.
A similar method is known from DE 27 14 511 C2. Here, the supply temperature is adapted to the highest heat requirement. For this purpose, an adjusting member is provided, which acts upon a mixing valve.
The invention is based on the task of keeping the energy consumption low.
With a method as mentioned in the introduction, this task is solved in that the number of rooms is ascertained, in which a heat requirement exists, and the supply temperature is increased by a value, which corresponds to a product of the number and a predetermined first temperature difference, when the number is higher than zero, and is reduced by a predetermined second temperature difference, when the number is equal to zero.
With this method, the supply temperature is kept very close to the actual requirement. Accordingly, losses, particularly transmission losses, which may result from a too high supply temperature, are relatively small. The heat requirement is continuously detected in all rooms. When there is no heat requirement in any if the rooms, it may be assumed that the supply temperature can be reduced. When a heat requirement exists in one room, it is assumed that this heat requirement can be satisfied faster, when the supply temperature is increased. In this case, the supply temperature is therefore increased. Additionally, the number of rooms is taken into consideration, in which the corresponding heat requirement exists. When, for example after a night-setback, the temperature must increase in several rooms at the same time, meaning that a heat requirement exists in several rooms, the supply temperature is increased more than in the case, when a heat requirement only exists in one room. Thus, the supplied energy can be even better adapted to the actual heat requirement.
Preferably, the supply temperature is kept constant for a predetermined period after a change. Thus, it is avoided that the supply temperature increases or reduces too fast because of a sudden and brief load change. Such a change of the load may, for example, occur, when a room is ventilated or exposed to a sudden, intensive sun irradiation. Only when a lasting change appears, the supply temperature is changed.
Preferably, the heat requirement of a room is detected from a position of, or a signal influencing a position of, a valve controlled in dependence of the temperature, said valve being allocated to the room in question. In connection with the valve, it will be sufficient to establish whether the valve is open or not. The size of the opening does not necessarily have to be considered. When the valve is open, a heat requirement exists. When the valve is closed, a heat requirement does not exist. In many cases, it is therefore not even necessary to detect the actual position of the valve. Particularly, when the valves can be remotely controlled, it is sufficient to check, if the valve has been opened or closed by the remote control. It is then not necessary to collect the information direct from the valve, the information, which is available otherwise, can be evaluated directly. On the other hand, the knowledge of the opening degree of the valve involves advantages, as it offers additional or better information about the actual heat requirement. The heat requirement can, for example, be detected by means of an LVDT transducer. In connection with floor heating systems, which are frequently controlled by means of on/off valves, the best result is obtained, when the time is considered, during which the valve in question is open. Thus, also information about the actual heat requirement is obtained. The same applies for pulsating or 0 to 10V activating elements. This means that the duty cycle, that is, the relation between the on- or opening time and the period length (sum of on- and off-times) can be detected. The optimum duty cycle can then be called reference time. This will depend on the application, with floor heating systems, for example, it will be in the range from 60 to 80%. When the opening time is lower than the reference time, that is, for example, the opening time is smaller than 80% of the period length, the supply temperature is reduced. When it is higher, the supply temperature is increased.
Preferably, the size of at least one of the temperature differences is chosen in dependence of the outdoor temperature. When, for example, it is very cold outside, it may be expedient to let the temperature increase by a higher value, when a heat requirement occurs, than would be the case in connection with a higher outdoor temperature. On the other hand, it can be expedient, in connection with a high outdoor temperature, to reduce the supply temperature in larger steps, than would be the case in connection with a lower outdoor temperature.
Preferably, the transmission of information about the heat requirement to the control device is wireless. This embodiment is particularly advantageous in connection with floor heating systems or combined heating systems, made up of floor heating and radiators, as here temperature sensors or thermostatic valves can be used, which are in radio contact with the control device. Particularly in connection with an upgrading the forcing open of walls and the running of cables can be avoided.
In a heating system as mentioned in the introduction, the task is also solved in that the control device has a counter, which counts the number of rooms, in which a heat requirement exists.
By means of the counter, it cannot only be established, if a heat requirement exists, which involves the necessity of increasing the supply temperature, it can also be quantitatively determined, how large the heat requirements Thus, the supply temperature can, in a simple manner, be increased in dependence of the number of rooms, in which a heat requirement exists.
Preferably, the control device has a time-relay, which prevents changes of the supply temperature for a predetermined period. This ensures that the supply temperature can be kept constant for a certain period after the changes, so that the changes of the supply temperature can become effective. Then the control device can detect again, if, and in how many rooms, a heat requirement exists, increasing or decreasing the supply temperature accordingly.
Preferably, the control device is in wireless connection with the valves. Thus, it is firstly ensured that the information required to adjust the valves is already available at the control device. This means that the counter can adopt values, which are already available in the control device.